Joe Ledley says he was planning to sign a new Celtic deal when they accepted a bid from Crystal Palace.
The Welsh international, whose deal was due to expire in the summer, sealed a January deadline day move to the Premier League outfit.
"They (Celtic) offered me a contract and I was actually planning on signing," the midfielder told BBC Wales.
"I spoke to Palace and, for me, it was the right time to go."
Ledley, 27, moved to Glasgow under freedom of contract in 2010, following six years at hometown club Cardiff City.
He helped Celtic win three league titles and last year's Scottish Cup.
But, after penning a three-and-a-half year deal at Selhurst Park, he said he was relishing playing in the "best league in the world".
"I enjoyed every moment at Celtic and it's a fantastic club. It will always be with me in my heart," said Ledley.
"I was sat there on deadline day and it came through that the club had accepted a bid. I just thought that it was right for me to go.
"When a club accepts (an offer) then, obviously, they want some money.
"So, I thought it was right for myself and for the club for me to move on and show the world, hopefully, what I can do in the Premier League.
"It was tough. I had the Champions League for a long time and won medals; then you're getting a bit older and at my age - hitting your potential - and I thought it was time for me to play in the Premier League."